Power supply unit arrangements comprising a main power supply unit and an auxiliary power supply unit are known. In particular, electronic appliances with a completely switched-on state and a so-called “standby” state and such a power supply unit arrangement are known. In that case, the auxiliary power supply unit performs the task of supplying power to the electronic appliance in the standby state, and the main power supply unit performs the task of supplying electricity to the electronic appliance in the operating state.
A problem with known power supply unit arrangements consists of feeding the voltage from the auxiliary power supply unit and the voltage from the main power supply unit to a common output of the power supply unit arrangement.
The provision of a voltage from an auxiliary power supply unit and a main power supply unit via a common output has several advantages. Inter alia, it is possible to dispense with the provision of an additional electrical contact between a power supply unit arrangement and the electronic appliance or its internal components if the output voltage of the auxiliary power supply unit is provided via an electrical output of the main power supply unit. Conversely, an output of an auxiliary power supply unit can be subjected to a greater load during operation if the main power supply unit in the switched-on state outputs a voltage generated by the main power supply unit in addition to an auxiliary voltage provided by the auxiliary power supply unit via this output. In addition, the consumer-side circuitry complexity can be reduced in both cases.
It could nonetheless be helpful to provide an improved power supply unit arrangement and a closed-loop control circuit for an auxiliary power supply unit which enable a voltage to be coupled in at a common output of a power supply unit arrangement, wherein energy efficiency of the power supply unit arrangement overall is maintained or improved.